The present embodiments relate to implantable medical devices and methods, and more particularly to an implantable medical device for the repair of a valve.
The aortic valve functions as a one-way valve between the heart and the rest of the body. Blood is pumped from the left ventricle of the heart, through the aortic valve, and into the aorta, which in turn supplies blood to the body. Between heart contractions the aortic valve closes, preventing blood from flowing backwards into the heart.
Damage to the aortic valve can occur from a congenital defect, the natural aging process, and from infection or scarring. Over time, calcium may build up around the aortic valve causing the valve not to open and close properly. Certain types of damage may cause the valve to “leak,” resulting in “aortic insufficiency” or “aortic regurgitation.” Aortic regurgitation causes extra workload for the heart, and can ultimately result in weakening of the heart muscle and eventual heart failure.
After the aortic valve becomes sufficiently damaged, the valve may need to be replaced to prevent heart failure and death. One current approach involves the use of a balloon-expandable stent to place an artificial valve at the site of the defective aortic valve. Another current approach involves the positioning of an artificial valve at the site of the aortic valve using a self-expanding stent. However, these techniques are imperfect. For example, the size of the implantation site depends on the unpredictable effects of a heavily calcified native valve and its annulus, and it may difficult for a self-expanding stent to seal within the annulus.
Further, balloon dilation of a stent at the site of the annulus may pose a problem when a valve is also implanted at the site of the annulus. In particular, balloon dilation of the stent at the site of the annulus may interfere with the valve and may compromise the functionality of the valve. Still further, when a balloon-expandable stent is loaded over a balloon in a delivery state, and the valve overlaps with the balloon-expandable stent, then the delivery profile of the system is increased by having the balloon, the stent, and the valve at the same axial location during delivery.